Devices for capture of milling debris generally involve the concept of circulation of fluid downhole so that cuttings carried by the fluid get captured in a screen while the cutting free flow continues to the surface. In essence, if the pump rate from the surface is for example 2 barrels a minute, a downhole recirculation rate of double that amount or more occurs through a screen. U.S. Pat. No. 6,276,452 illustrates that this is accomplished with a device called a jet bushing which takes the pressurized clean fluid pumped downhole and directs it downwardly and radially out through housing ports in the tool. This action induces flow laden with cuttings to enter the tool below a screen so that the cuttings can be retained as the fluid continues through the screen.
FIG. 1 is a partial view of the tool illustrated in U.S. Pat. No. 6,276,452 in the area of the jet bushing to show the problem addressed by the present invention. It shows part of a casing 10 and part of a tool body 12 that holds the jet bushing 14. A series of downwardly and outwardly facing openings 16 are aligned with matching ports 18 so that flow represented by arrow 20 can make a lateral exit in the downhole direction. This arrangement is akin to the nozzles 34 in U.S. Pat. No. 6,276,452 sending flow through aligned ports 24. Referring again to FIG. 1 a recirculation flow pattern is set up as indicated by arrow 22 going down the annulus 24 and coming back up the tool through a screen (not shown) in a central passage 26 as represented by arrows 28. Of course, the flow rate going into the tool represented by arrow 30 has to be the same as the flow rate coming back up to the surface represented by arrow 32, assuming no fluid losses downhole. It should be noted that the flow represented by arrow 20 has to come back up the hole as shown by arrow 32. However, at the port 18 that flow mixes with recirculating flow 28 and that reversal of direction to go uphole in the same region as the recirculation flow is trying to go downhole causes turbulence that reduces the overall recirculation flow 28.
Thus, the present invention optimizes the configuration of the jet bushing to optimize the recirculation flow by decreasing the turbulence created by the prior design. It simply provides at least one nozzle oriented uphole to accommodate the recirculation loop without any part of it having to reverse direction after exiting the tool housing. These features will be more readily understood by those skilled in the art from a review of the description of the preferred embodiment and the associated drawing with the understanding that the claims are the full measure of the invention.